The present invention relates to a water-absorbent carrier, a method for manufacturing the water-absorbent carrier, a medical article packaged with the water-absorbent carrier in a space to be sterilized, and a moist heat sterilization method. The water-absorbent carrier is provided in a part over which water vapor cannot readily spread during the moist heat sterilization.
Conventionally, it is known as a rule of thumb that spore bacteria can survive in a dry condition even at a high temperature of, for example, 121° C. Therefore, a moist heat sterilization method has been employed for the purpose of sterilizing a part not containing water within a packaging bag for a medical article to be sterilized in such a way that a nonwoven fabric or the like having a good water vapor transmittance is used as at least a part of the packaging bag to introduce water vapor that serves as a sterilant.
During the moist heat sterilization, water vapor denatures a protein component and a nucleic acid structure of a microorganism, thereby killing the microorganism. Therefore, a technique for spreading heated water vapor over a part to be sterilized has been required. As mentioned above, water vapor functions as a sterilant for the moist heat sterilization. In particular, it can be said that saturated water vapor functions as a sterilant for moist heat sterilization (autoclave sterilization).
However, such a conventional packaging bag suffers from propagation of mold or the like due to damage to the nonwoven fabric and insufficient drying after sterilization. Therefore, it has been necessary to dry the packaging bag including the inside thereof for a certain period of time after the sterilization process.
In JP 59-041744 B (“Patent Literature 1”), a “medical item packaging body” has been proposed as a means to solve this problem. Specifically, a medical article is packaged in an airtight manner using a flexible material which does not substantially transmit water vapor (e.g. polypropylene, polyethylene, nylon, polyester, polyvinyl chloride, or a laminated body including other synthetic resins), and a water-absorbent body (filter paper) preliminarily containing water is contained in the package.
JP 05-014585 B (“Patent Literature 2”) has introduced a “heating sterilization method for a container”. Specifically, a container is closely packaged in an exterior body together with silica gel into which water is absorbed or on which water is carried. The exterior body is then heated for a certain period of time at a temperature of 50° C. or higher, and naturally cooled at room temperature. In Patent Literature 2, more specifically, silica gel into which water is absorbed or on which water is carried is put in a bag made of polyethylene, and an opening of the bag is sealed with a rubber band, and closely packaged in the exterior body together with an object to be sterilized (container). The exterior body is then heated for a certain period of time at a temperature of 50° C. or higher, and left to cool at room temperature.
Furthermore, JP 2003-052819 A (“Patent Literature 3”) has proposed a “package for an injector filled with a medicine and sterilization of the same or a sterilization method therefore”. Specifically, a prefilled syringe is vacuum-packaged and sterilized in order to prevent water from remaining in a cap or a nozzle when sterilizing the prefilled syringe. In Patent Literature 3, it is described that a temperature sensor placed in a syringe body indicates a temperature of 121° C.